The present invention relates generally to medical/dental prosthetics and processes for preparing such prosthetics, including tooth prostheses. More particularly, the present invention concerns an implant assembly which includes a tubular body portion that can be positively secured within a bore in a bone by an expander mechanism, and a unique transfer technique for preparing a prosthetic device.
Dental implants of the character receivable within a bore provided in the jawbone are old in the art. Typically such implants comprise an apertured body portion which is emplaced within a bore drilled in the bone. The body portion is designed so that during a period of about four to six months after its emplacement within the bore, bone tissue will grow into the aperture so as to secure the body portion of the implant in place within the bone bore. Following this four to six month period, an artificial tooth or other prosthetic component is secured to the body portion.
The procedure is undesirable in several respects. In the first place, the procedure is protracted and requires multiple visits to the oral surgeon. Secondly, during the extended period of time required for the bone tissue to grow into and around the implant, the patient is left with an uncomfortable and unsightly cavity where the prosthetic component, such as an artificial tooth, will eventually go. Additionally, this procedure does not always provide adequate anchoring of the implant to the jawbone so that in time the implant can loosen.
In order to overcome the drawbacks of the standard procedure described above, several types of implants using mechanical locking means for securing the implant in place within the bore in the jawbone have been suggested. Exemplary of such devices is the device described in U.S. Pat. No. 3,708,883 issued to Flander. An improved dental implant is illustrated and described in U.S. Pat. Nos. 5,004,421 and 5,807,199 issued to Lazarof. The Lazarof dental implant makes use of mechanical securement means, but unlike the Flander device, the Lazarof device includes means by which selected dental prosthetics of standard design can be threadably interconnected. In this way, angular corrections of the prosthetic, such as an artificial tooth, can readily be made. Further, in one form, the Lazarof implant is positively secured within the bore in the bone by two separate but cooperating securement mechanisms. The first securement mechanism comprises self-tapping, external threads provided on the tubular body of the device which are threaded into the bone by rotating the device in a first direction. The second cooperating securement mechanism comprises a plurality of bone penetrating anchor blades formed on the skirt portion of the tubular body which are moved into a bone engagement position only after the implant has been securely threaded into the bone. The anchor blades are moved into the bone engagement configuration by rotating a threaded expander member also in a first direction. However, because the threads on the expander member are opposite to the threads on the tubular body, rotational forces exerted on the expander member continuously urge the implant in a tightening direction. In other words, as the anchor blades are urged outwardly, the implant is continuously urged into threaded engagement with the bone. This double locking approach permits the selected prosthetic component to be connected to the implant immediately without the patient having to return to the oral surgeon a second time.
Often an abutment over which a tooth prosthesis is formed, is fixed to an exposed end of the dental implant. Typically, the prior abutments either accommodated a bolt which passed longitudinally through an open central bore for securing the abutment to the implant, or were provided an integral threaded shaft to permit the abutment to be screwed directly into the implant. Such abutment to implant attachment has not been entirely satisfactory, however, since it is very undesirable that any relative movement between the abutment and the implant be permitted once brought together, and particularly after a prosthesis has been attached to the abutment. Without actually cementing the abutment to the implant, there always exists the possibility that the abutment will loosen, resulting in undesirable rotation of the dental prosthesis.
Since dental prosthetic devices are typically manufactured in a laboratory, a major concern of dentists and laboratory technicians is the accurate transfer of information from the patient/dentist to the lab. Such information includes the size and shape of adjacent teeth, the position of the implant and the precise configuration of the abutment, since it is often shaped by the dentist in preparation.
Accordingly, there has been a need for an improved prosthetic implant assembly which is of simplified construction and which incorporates advantages over the prior art. Further, there exists a need for a novel process for preparing a prosthetic device. The present invention fulfills these needs and provides other related advantages.